[stable/prometheus] extra environment variable for alert manager (#1237)

* Added a map of extra environment variable for the alertmanager, this is needed to add the http_proxy so alert manager can connect to external applications if behind a proxy

* Update Chart.yaml

stable/prometheus/Chart.yaml

@@ -1,5 +1,5 @@
 name: prometheus
-version: 3.0.2
+version: 3.0.3
 description: Prometheus is a monitoring system and time series database.
 home: https://prometheus.io/
 icon: https://raw.githubusercontent.com/prometheus/prometheus.github.io/master/assets/prometheus_logo-cb55bb5c346.png

stable/prometheus/templates/alertmanager-deployment.yaml

@@ -26,6 +26,11 @@ spec:
         - name: {{ template "prometheus.name" . }}-{{ .Values.alertmanager.name }}
           image: "{{ .Values.alertmanager.image.repository }}:{{ .Values.alertmanager.image.tag }}"
           imagePullPolicy: "{{ .Values.alertmanager.image.pullPolicy }}"
+          env:
+            {{- range $key, $value := .Values.alertmanager.extraEnv }}
+            - name: {{ $key }}
+              value: {{ $value }}
+            {{- end }}
           args:
             - --config.file=/etc/config/alertmanager.yml
             - --storage.path={{ .Values.alertmanager.persistentVolume.mountPath }}

stable/prometheus/values.yaml

@@ -18,6 +18,11 @@ alertmanager:
   ##
   extraArgs: {}
 
+  ## Additional alertmanager container environment variable
+  ## For instance to add a http_proxy
+  ##
+  extraEnv: {}
+
   ingress:
     ## If true, alertmanager Ingress will be created
     ##